1. Technical Field
The invention relates to an ink jet recording method and an ink set preferable for the ink jet recording method.
2. Related Art
As one printing apparatus that forms images by ejecting inks onto recording media, there is known an ink jet printer. In addition, among the ink jet printers, as a printer that can perform high speed printing, a line printer has been used. The line printer uses one or more printing heads (hereinafter, referred to as a “line head”) that realize nozzle arrays having lengths corresponding to the length of the recording medium in the width direction (direction orthogonal to transportation direction), transports the recording medium to the line heads, and performs printing on the recording medium without the movement of the line heads in the direction orthogonal to the transportation direction.
In the line printer having the configuration, since printing is performed generally in one pass without performing two or more instances of superimposed printing, the ink weight of one dot has to be great in order to secure solid filling. Then, there is a problem in that a bleeding phenomenon between inks easily occurs.
As means for solving the problem, an image recording method of forming an image by causing the dynamic surface tensions of respective inks used in a line printer to be 37 mN/m to 48 mN/m, and ejecting two or more kinds of inks between which the dynamic surface tension differences are all 2 mN/m or greater in a sequence beginning with an ink having a larger dynamic surface tension has been proposed in JP-A-2013-107224.
However, in the technique disclosed in JPA-2013-107224, the generation of bleeding between black and colors is suppressed, but the bleeding between colors widely occurs. The bleeding of black ink is okay as long as the black ink is not spread to the color inks (that is, the color inks may be spread to the black ink), but the bleeding between colors may not be generated in a manner in which at least three colors of inks spread to each other.
In addition, in the line printer, since the ink weight of one dot has to be great in order to secure the solid filling thereof, in the inks in which only the dynamic surface tension is controlled as in the inks disclosed in JP-A-2013-107224, bleed-through of the inks in the recording medium may occur. In addition, the “bleed-through” in the specification refers to a state in which the ink permeates the recording medium to the backside.
After the ink droplet lands on the recording medium to reach the equilibrium state, the static surface tension is more dominant than the dynamic surface tension of the ink. That is, before the ink droplet reaches the equilibrium state, since amphiphilic substances such as a surfactant are not regularly oriented on the gas-liquid interface of the ink droplet, the dynamic surface tension becomes dominant. Meanwhile, after the ink droplet reaches to an equilibrium state, amphiphilic substances are regularly oriented on the gas-liquid interface of the ink droplet, and thus the static surface tension becomes more dominant.